This invention relates in general to a metered liquid dispensing system and, in particular, to a positive displacement gear pump for use in such a system.
Chemical treatment of crops is extensively used in the field of agriculture. Two major areas in which chemical treatments are used are fertilization and insect control. In order to minimize distribution costs, the chemicals are usually sold to the distributor in bulk shipments of concentrated liquid. The distributor then dispenses smaller portions of the concentrate to the farmer by pumping the needed amount from a bulk storage tank. The farmer adds water to dilute the chemicals to the proper concentration before applying them to his crops.
To get maximum effect from the chemical without damaging the crop, the amount of chemical used is extremely critical. The chemical manufacturer will specify the desired ratio of chemical to water that should be used. The total amount of chemical needed is then calculated and dispensed based upon the total volume of the farmer's container. Furthermore, because the chemicals are concentrated, they can be very expensive. Thus, precise control and accurate measurement of the amount delivered to the farmer is important. Careful handling is needed because, in their concentrated form, the chemicals could have an adverse effect upon the environment and anyone coming into contact with them if spilled.